521666601657 has 16 divisors (see below), whose sum is σ = 717217478208. Its totient is φ = 337104847040.

The previous prime is 521666601653. The next prime is 521666601661. The reversal of 521666601657 is 756106666125.

It is an interprime number because it is at equal distance from previous prime (521666601653) and next prime (521666601661).

It is a cyclic number.

It is not a de Polignac number, because 521666601657 - 2² = 521666601653 is a prime.

It is not an unprimeable number, because it can be changed into a prime (521666601653) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19751394 + ... + 19777787.

It is an arithmetic number, because the mean of its divisors is an integer number (44826092388).

Almost surely, 2^521666601657 is an apocalyptic number.

It is an amenable number.

521666601657 is a deficient number, since it is larger than the sum of its proper divisors (195550876551).

521666601657 is a wasteful number, since it uses less digits than its factorization.

521666601657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39529320.

The product of its (nonzero) digits is 2721600, while the sum is 51.

The spelling of 521666601657 in words is "five hundred twenty-one billion, six hundred sixty-six million, six hundred one thousand, six hundred fifty-seven".